What is sleep apnea?
Sleep apnea is a disorder characterized by a reduction or pause of breathing (airflow) during sleep. It is common among adults but rare among children. Although a diagnosis of sleep apnea often will be suspected on the basis of a person's medical history, there are several tests that can be used to confirm the diagnosis. The treatment of sleep apnea may be either surgical or nonsurgical.

An apnea is a period of time during which breathing stops or is markedly reduced. In simplified terms, an apnea occurs when a person stops breathing for 10 seconds or more. If you stop breathing completely or take less than 25% of a normal breath for a period that lasts 10 seconds or more, this is an apnea. This definition includes complete stoppage of airflow. Other definitions of apnea that may be used include at least a 4% drop in oxygen in the blood, a direct result of the reduction in the transfer of oxygen into the blood when breathing stops.

Apneas usually occur during sleep. When an apnea occurs, sleep usually is disrupted due to inadequate breathing and poor oxygen levels in the blood. Sometimes this means the person wakes up completely, but sometimes this can mean the person comes out of a deep level of sleep and into a more shallow level of sleep. Apneas are usually measured during sleep (preferably in all stages of sleep) over a two-hour period. An estimate of the severity of apnea is calculated by dividing the number of apneas by the number of hours of sleep, giving an apnea index (AI in apneas per hour); the greater the AI, the more severe the apnea.

A hypopnea is a decrease in breathing that is not as severe as an apnea. Hypopneas usually occur during sleep and can be defined as 69% to 26% of a normal breath. Like apneas, hypopneas also may be defined as a 4% or greater drop in oxygen in the blood. Like apneas, hypopneas usually disrupt the level of sleep. A hypopnea index (HI) can be calculated by dividing the number of hypopneas by the number of hours of sleep.

The apnea-hypopnea index (AHI) is an index of severity that combines apneas and hypopneas. Combining them gives an overall severity of sleep apnea including sleep disruptions and desaturations (a low level of oxygen in the blood). The apnea-hypopnea index, like the apnea index and hypopnea index, is calculated by dividing the number of apneas and hypopneas by the number of hours of sleep.

Another index that is used to measure sleep apnea is the respiratory disturbance index (RDI). The respiratory disturbance index is similar to the apnea-hypopnea index; however, it also includes respiratory events that do not technically meet the definitions of apneas or hypopneas, but do disrupt sleep.

What are the types of sleep apnea?

There are three types of sleep apnea:

1. central sleep apnea (CSA),

2. obstructive sleep apnea (OSA), and

3. mixed sleep apnea (both central sleep apnea and obstructive sleep apnea).

During sleep, the brain instructs the muscles of breathing to take a breath.

• Central sleep apnea (CSA) occurs when the brain does not send the signal to the muscles to take a breath, and there is no muscular effort to take a breath.
   

• Obstructive sleep apnea (OSA) occurs when the brain sends the signal to the muscles and the muscles make an effort to take a breath, but they are unsuccessful because the airway becomes obstructed and prevents an adequate flow of air.
   

• Mixed sleep apnea, occurs when there is both central sleep apnea and obstructive sleep apnea.

What are the non-surgical treatments for obstructive sleep apnea?

The non-surgical treatments for obstructive sleep apnea are similar to the non-surgical treatments for snoring with a few differences. Treatments include:

• behavioral changes,
   
• dental appliances,
   
• CPAP (continuous positive airway pressure), and
   
• medication.